The present invention is directed to an X-Y plotter having a pen changer, and, in particular, to a pen charger for an X-Y plotter which is simple in construction and quickly operable for permitting fast and easy changing of pens.
As shown in FIGS. 12A and 12B of the drawings, a conventional X-Y plotter, generally indicated as 200, includes a plurality of pens 1, individually identified as 1a, 1b, 1c, 1d, a rotatable holder 2 supporting pens 1, a carriage 3 slidable on rods 3a and carrying rotatable holder 2, a pen return spring 4 fixed to holder 2, a hammer 6 with a slide roller 5, and a drive plate 7 for actuating hammer 6. When a solenoid is energized to produce an attractive or repulsive force, drive plate 7 is angularly moved in the direction of arrow A to move slide roller 5 in the same direction. Hammer 6 is then turned in the direction of arrow B to thereby cause pen 1a to slide in the direction of arrow C until it is pressed against a sheet of paper.
When pens are to be changed in this prior art structure, carriage 3 must be physically moved to one of the side walls of the plotter frame to enable a leaf spring 8 fixed to the side wall to turn teeth or notches 9 on the periphery of holder 2 one notch at a time in the direction of arrow D. A desired pen 1 is thus brought into and kept in a print position by a rotation stop leaf spring 10 and an inner indexing mechanism (not shown).
The prior art pen changer in X-Y plotters is disadvantageous in that the carriage has to be reciprocably moved toward and away from the side wall to turn holder 2 the required number of notches or teeth until a desired pen is reached. A sensor is required to be installed between the holder and the side wall for detecting pen numbers. After the X-Y plotter has been used, the pen should be removed and covered with caps which places a limitation on the use of the plotter.
Accordingly, the present invention provides an improved pen changer for use in X-Y plotters which overcomes the disadvantages of the prior art.